Showing papers by "Trakya University published in 2008"

Comparing performances of logistic regression, classification and regression tree, and neural networks for predicting coronary artery disease

Abstract: In this study, performances of classification techniques were compared in order to predict the presence of coronary artery disease (CAD). A retrospective analysis was performed in 1245 subjects (865 presence of CAD and 380 absence of CAD). We compared performances of logistic regression (LR), classification and regression tree (CART), multi-layer perceptron (MLP), radial basis function (RBF), and self-organizing feature maps (SOFM). Predictor variables were age, sex, family history of CAD, smoking status, diabetes mellitus, systemic hypertension, hypercholesterolemia, and body mass index (BMI). Performances of classification techniques were compared using ROC curve, Hierarchical Cluster Analysis (HCA), and Multidimensional Scaling (MDS). Areas under the ROC curves are 0.783, 0.753, 0.745, 0.721, and 0.675, respectively for MLP, LR, CART, RBF, and SOFM. MLP was found the best technique to predict presence of CAD in this data set, given its good classificatory performance. MLP, CART, LR, and RBF performed better than SOFM in predicting CAD in according to HCA and MDS.

Comparison of the health-promoting lifestyles of nursing and non-nursing students in Istanbul, Turkey.

Abstract: Undertaking a health-related course at university can facilitate an awareness of health-promoting lifestyles. We carried out a descriptive and cross-sectional study with 1616 university students in Istanbul, Turkey. Students from the nursing schools were compared to those from the schools of social sciences using a Turkish version of the Health-promoting Lifestyle Profile (HPLP) II after a validation study. The nursing students had more positive health-promoting lifestyles than those of the non-nursing students. Furthermore, fourth-year nursing students had higher scores in most of the subscales of the HPLP II than did the students from the lower years; conversely, the fourth-year non-nursing students had lower scores. The sociodemographic variables, self-perceived health status, relations with family and friends, and self-perceived academic performance were associated with the HPLP. The implications are discussed for the curricula and on-campus facilities that focus on health promotion activities.

Nigella sativa and derived thymoquinone prevents hippocampal neurodegeneration after chronic toluene exposure in rats.

Abstract: The aim of this study was designed to investigate the possible beneficial effects of Nigella sativa (NS) and derived thymoquinone (TQ) on neurodegeneration in hippocampus after chronic toluene exposure in rats. The rats were randomly allotted into one of four experimental groups: A (control), B (toluene treated), C (toluene treated with NS) and D (toluene treated with TQ); each group contain 10 animals. Toluene treatment was performed by inhalation of 3,000 ppm toluene, in a 8 h/day and 6 day/week order for 12 weeks. Control group received 1 ml serum physiologic and the rats in NS and TQ treated groups (C and D) were given NS (in a dose of 400 mg/kg body weight) and TQ (50 mg/kg body weight) once a day orally by using intra gastric intubation for 12 weeks starting just after toluene exposure respectively. Tissue samples were obtained for histopathological investigation. To date, no histopathological changes of neurodegeneration in hippocampus after chronic toluene exposure in rats by NS and TQ treatment have been reported. In this study, chronic toluene exposure caused severe degenerative changes, shrunken cytoplasma, slightly dilated cisternae of endoplasmic reticulum, markedly swollen mitochondria with degenerated cristae and nuclear membrane breakdown with chromatin disorganization in neurons of the hippocampus. The distorted nerve cells were mainly absent in the TQ and NS-treated rats. We conclude that TQ and especially NS therapy causes morphologic improvement on neurodegeneration in hippocampus after chronic toluene exposure in rats. We believe that further preclinical research into the utility of NS and TQ may indicate its usefulness as a potential treatment on neurodegeneration after chronic toluene exposure in rats.

Effects of Nigella sativa and its Major Constituent, Thymoquinone on Sciatic Nerves in Experimental Diabetic Neuropathy

Abstract: The aim of this study was designed to investigate the possible beneficial effects of Nigella sativa (NS) and thymoquinone (TQ) on histopathological changes of sciatic nerves in streptozotocin-induced diabetic rats. The rats were randomly allotted into one of four experimental groups: A (control), B (diabetic untreated), C (diabetic treated with NS) and D (diabetic treated with TQ); each group contain ten animals. B, C and D groups received streptozotocin (STZ) to induce diabetes. The rats in NS and TQ treated groups were given NS (in a dose of 400 mg/kg body weight) and TQ (50 mg/kg body weight) once a day orally by using intra-gastric intubation for 12 weeks starting 2 days after STZ injection, respectively. Blood and tissue samples were obtained for biochemical and histopathological investigation. The treatment of both NS and TQ caused a sharp decrease in the elevated serum glucose (P < 0.01, 0.05, respectively), and an increase in the lowered serum insulin concentrations (P < 0.01, 0.05, respectively), in STZ-induced diabetic rats. STZ induced a significant decrease in the area of insulin immunoreactive β-cells (P < 0.0001). NS (P < 0.001) and TQ (P < 0.01) treatment resulted in increased area of insulin immunoreactive β-cells significantly. To date, no histopathological changes of sciatic nerves in STZ induced diabetic rats by NS and TQ treatment have been reported. In this study, histologic evaluation of the tissues in diabetic animals treated with TQ and especially NS showed fewer morphologic alterations. Myelin breakdown decreased significantly after treatment with NS and TQ. The ultrastructural features of axons also showed remarkable improvement. We believe that further preclinical research into the utility of NS and TQ may indicate its usefulness as a potential treatment on peripheral neuropathy (PN) in STZ induced diabetic rats.

Influence of Reading Attitude on Reading Achievement: A Test of the Temporal-Interaction Model.

Abstract: Despite widespread efforts to prevent reading problems and an abundance of research about best practices in remediating reading skills deficits, reading continues to be exceptionally difficult for many students. Researchers have become interested in investigating the degree to which affective factors such as reading attitude relates to reading performance. In the current study, 76 fourth-grade students were administered Curriculum-Based Measurement tasks in reading (R-CBM) and the Elementary Reading Attitude Survey (ERAS; McKenna & Kear, 1990, 1999). In the fall of the following school year (4 months later), participants completed a high-stakes statewide reading assessment. Descriptive statistics, Pearson correlations, and a path analysis were computed to address the research questions. Results indicated that both reading ability (β = .62, p = .01) and reading attitude significantly predicted reading achievement (Indiana Statewide Testing for Educational Progress-Plus;ISTEP+) 4 months later (β = .22, p = .01), supporting a temporal interactive effect (Kush, Watkins, & Brookhart, 2005) of prior reading attitude and skill on later reading achievement. Additional findings, implications for practice, directions for future research, and limitations of the study are discussed. © 2008 Wiley Periodicals, Inc.

Matrix metalloproteinase 9 (MMP9) expression in preeclamptic decidua and MMP9 induction by tumor necrosis factor alpha and interleukin 1 beta in human first trimester decidual cells.

Abstract: Extravillous trophoblasts (EVTs) invade human decidua via sequential integrin-mediated binding and proteolysis of basement membrane proteins in the extracellular matrix (ECM). In preeclampsia, shallow EVT invasion impairs spiral artery and arteriole remodeling to reduce uteroplacental blood flow. Excess decidual cell-expressed matrix metalloproteinases (MMPs) 2 and 9, in response to preeclampsia-related interleukin 1 beta (IL1B) and tumor necrosis factor alpha (TNF), may inappropriately degrade these basement membrane proteins and impede EVT invasion. This study found significantly higher immunohistochemical MMP9 levels in decidual cells and adjacent interstitial trophoblasts in placental sections of preeclamptic versus gestational age-matched control women. In contrast, immunostaining for MMP2 and tissue inhibitor of matrix metalloproteinases 1 and 2 (TIMP1 and TIMP2) were similar in preeclamptic and control groups. First-trimester decidual cells were incubated with estradiol (E(2)) or E(2) + medroxyprogesterone acetate (MPA), with or without TNF or IL1B. As measured by ELISA, both cytokines elicited concentration-dependent increases in secreted MMP9 levels that were unaffected by MPA. In contrast, secreted levels of MMP2, TIMP1, and TIMP2 were unchanged in all treatment groups. Substrate gel zymography and Western blotting confirmed that each cytokine increased secreted levels of MMP9 but not MMP2. Similarly, quantitative RT-PCR found that TNF and IL1B enhanced MMP9, but not MMP2, mRNA levels. At the implantation site, inflammatory cytokine-enhanced MMP9 may promote preeclampsia by disrupting the decidual ECM to interfere with normal stepwise EVT invasion.

The evolution of invasiveness in garden ants.

Abstract: It is unclear why some species become successful invaders whilst others fail, and whether invasive success depends on preadaptations already present in the native range or on characters evolving de-novo after introduction. Ants are among the worst invasive pests, with Lasius neglectus and its rapid spread through Europe and Asia as the most recent example of a pest ant that may become a global problem. Here, we present the first integrated study on behavior, morphology, population genetics, chemical recognition and parasite load of L. neglectus and its non-invasive sister species L. turcicus .W e find that L. neglectus expresses the same supercolonial syndrome as other invasive ants, a social system that is characterized by mating without dispersal and large networks of cooperating nests rather than smaller mutually hostile colonies. We conclude that the invasive success of L. neglectus relies on a combination of parasite-release following introduction and preadaptations in mating system, body-size, queen number and recognition efficiency that evolved long before introduction. Our results challenge the notion that supercolonial organization is an inevitable consequence of low genetic variation for chemical recognition cues in small invasive founder populations. We infer that low variation and limited volatility in cuticular hydrocarbon profiles already existed in the native range in combination with low dispersal and a highly viscous population structure. Human transport to relatively disturbed urban areas thus became the decisive factor to induce parasite release, a well established general promoter of invasiveness in non-social animals and plants, but understudied in invasive social insects.

Semi-inverse Method for Vibration and Buckling of Axially Functionally Graded Beams

Abstract: In this study, vibration and buckling of axially functionally graded simply supported beams is analyzed by using the semi-inverse method. Euler—Bernoulli beam theory was used in the analysis. By using a pre-specified frequency and buckling loads, variation of the Young's modulus in the axial direction is obtained in terms of the axial coordinate. It is found that the Young's modulus changes exponentially between the edges of the beam for the vibration and buckling problem.

Oxidative stress in the blood of patients with active localized vitiligo.

Abstract: Objectives: Vitiligo is an acquired skin disease characterized by white areas on the skin. The pathogenesis of the disease is still unclear. Some findings show that oxidative stress could be an important phenomenon in the pathophysiology of vitiligo. Methods: We evaluated 16 consecutive localized vitiligo patients and 16 healthy controls of a similar age and sex distribution. We measured their indicators of oxidative stress such as catalase (CAT), superoxide dismutase (SOD), glucose 6-phosphate dehydrogenase (G6PD) in erythrocytes, and plasma malondialdehyde (MDA) by spectrophotometry. Results: SOD activities and MDA levels of patients were significantly higher than controls (p < 0.001). CAT and G6PD activities of patients were significantly lower than controls (p < 0.05 and p < 0.001, respectively). Conclusion: Our results confirmed that oxidative stress may play an important role in the pathogenesis of vitiligo. Melanocyte damage in vitiligo might be linked to generalized oxidative stress. This study is the first report on some antioxidant parameters of localized-type vitiligo patients.

A Sensory Integration Therapy Program on Sensory Problems for Children with Autism

Abstract: The study was planned to investigate the effect of a sensory integration therapy program on sensory problems of children with autism. This study was conducted at the Trakya University Training and Research Center for Mentally and Physically Handicapped Children in Turkey. The children were separated into two groups, each comprising 15 children between 7 and 11 years of age with autism, according to DSM-IV criteria. The children in each group were assessed initially on a checklist, Sensory Evaluation Form for Children with Autism, developed to evaluate sensory characteristics of children with autism, and at the end of the study, participants were assessed again on the checklist. Statistically significant differences between groups indicated that the sensory integration therapy program positively affected treated children.

Progestin-inflammatory cytokine interactions affect matrix metalloproteinase-1 and -3 expression in term decidual cells: implications for treatment of chorioamnionitis-induced preterm delivery.

Abstract: Context: Chorioamnionitis (CAM)-elicited preterm delivery (PTD) is associated with elevated amniotic fluid levels of IL-1β and TNF-α. We hypothesized that IL-1β and TNF-α may induce matrix metalloproteinase (MMP)-1 and MMP-3 activity to promote PTD by degrading decidual and fetal membranes and cervical extracellular matrix. Objective: Our objective was to evaluate: 1) MMP-1 and MMP-3 expression in decidual sections from uncomplicated term, idiopathic preterm, and CAM-complicated deliveries, and 2) the separate and interactive effects of IL-1β, TNF-α, medroxyprogesterone acetate (MPA), and a p38 MAPK inhibitor (SB203580) on MMP-1 and MMP-3 expression in term decidual cells (DCs). Interventions and Main Outcome Measures: Decidua were immunostained for MMP-1 and MMP-3. Cultured term DCs were incubated with estradiol (E2) or E2 plus MPA with or without IL-1β or TNF-α with or without SB203580. ELISA and Western blotting assessed secreted MMP-1 and MMP-3 levels, quantitative real-time RT-PCR assessed mRNA level...

Airborne fungi in child day care centers in Edirne City, Turkey.

Abstract: The purpose of this study was to determine the concentration, in terms of monthly and seasonal distribution and in relation to meteorological factors, of indoor and outdoor microfungi at selected sites in several child day care centers in the city of Edirne, Turkey Samples were collected at one month intervals over a period of 12 months between January-December 2004, by exposing petri plates containing Peptone Dextrose Agar with Rose-Bengal and Streptomycin medium to the air for 10-15 min A total of 2,071 microfungal colonies were counted on 192 petri plates Thirty microfungal genera (Acremonium, Alternaria, Arthrinium, Aspergillus, Bahusakala, Beauveria, Ceuthospora, Chaetomium, Cladosporium, Curvularia, Drechslera, Epicoccum, Eurotium, Fusarium, Mycotypha, Myrotechium, Paecilomyces, Penicillium, Pestalotiopsis, Phoma, Ramichloridium, Rhizopus, Scopulariopsis, Stachybotrys, Stemphylium, Torula, Trichoderma, Trichothecium, Ulocladium, Verticillium) and 75 microfungal species were isolated from the air indoor and outdoor of the day care centers The dominant microfungal genera were Cladosporium, Penicillium and Alternaria (4411%, 1894%, 1467% of the total respectively), while the genus with the most species richness was Penicillium (26 species) Alternaria, Cladosporium, Penicillium and non-sporulating microfungi were found every month Cladosporium was the dominant genus in both indoor and outdoor air Although the predominant genus was the same in both indoor and outdoor air, Cladosporium was followed by Penicillium, Alternaria and Aspergillus genera in indoor air and by Alternaria, Penicillium and Aspergillus genera in outdoor air While a positive correlation was found between the concentration of monthly outdoor microfungi and monthly average temperature, a negative correlation was found between the concentration of monthly outdoor microfungi and monthly average wind velocity Also, some relationships were found between the monthly concentrations of the most predominant microfungal genera (Cladosporium, Penicillium and Alternaria) and various meteorological factors

Increased platelet activation markers in rheumatoid arthritis: are they related with subclinical atherosclerosis?

Abstract: Atherosclerotic cardiovascular mortality is increased in rheumatoid arthritis (RA) patients We evaluated the association of inflammatory response with platelet, endothelial, coagulation activation parameters; and subclinical atherosclerosis in RA patients We included 27 RA patients (21 female; six male) and 19 healthy subjects (14 female; five male) Disease activity score (DAS28) in RA patients was calculated; and patients were divided into two groups as active and inactive Flow cytometry was used to determine platelet CD62P expression, platelet microparticles (PMP), platelet-monocyte (PMC) and platelet-neutrophil complexes (PNC) Plasma E-selectin, thrombin-antithrombin (TAT) complex, and serum sCD40L levels were determined by ELISA The intima-media thickness (IMT) of carotid arteries was determined by B-mode ultrasonography In RA patients, platelet CD62P expression (p 005)The increase in markers of active platelets, CD62P and sCD40L, and PMC levels might be associated with the increased cardiovascular mortality in RA Nevertheless, none of these parameters were associated with carotid IMT: this suggests that one cross-sectional value might not be a good marker for atherosclerosis

The binding energy of hydrogenic impurity in multilayered spherical quantum dot

Abstract: The binding energy of a hydrogenic impurity of a multilayered spherical GaAs-(Ga,Al)As quantum dot has been investigated as a function of the barrier thickness and the inner dot thickness for various barrier potentials in the effect of the band non-parabolicity. Within the effective mass approximation, the ground state energy has been calculated using the fourth-order Runge–Kutta method. The ground state binding energy of hydrogenic impurity located at the center of a quantum dot has been studied with a variational approach. We have found that a variation in the binding energy has depended on the geometry of the dot.

Clinical and prognostic features of plasmacytomas: A multicenter study of Turkish Oncology Group‐Sarcoma Working Party

Abstract: To identify the outcomes of prognostic factors of solitary plasmacytoma mainly treated with local radiotherapy (RT). The data were collected from 80 patients with solitary plasmacytoma (SP). Forty patients (50.0%) received radiotherapy (RT) alone while 38 of them (47.5%) were treated with surgery (S) and RT. The median radiation dose was 46 Gy (range 30-64). The median follow up was 2.41 years (range 0.33-12.33). Ten-year overall survival (OS) and local relapse-free survival (LRFS) were 73% and 94%, respectively. The median progression-free survival (PFS) and multiple myeloma-free survival (MMFS) were 3.5 years and 4.8 years, respectively. On multivariate analyses, the favorable factors were radiotherapy dose of > or =50 Gy and RT + S for PFS and younger age for MMFS. For the patients with medullary plasmacytoma, the favorable factor was younger age for MMFS. RT at > or =50 Gy and RT + S may be favorable prognostic factors on PFS. Younger patients, especially with head-neck lesion and without pre-RT macroscopic tumor, seem to have the best outcome when treated with RT +/- S. Progression to MM remains as the main problem especially for older patients.

Low leptin levels in migraine: a case control study.

Abstract: Background.— Obesity has been shown to be a risk factor for transformation of episodic migraine to chronic form, and adipocytokines have been implicated to modulate some of the cytokins such as interleukin-6 and tumor necrosis factor, which also act in the neurogenic inflammation in migraine. The aim of the study was to assess leptin levels, one of the adipocytokines, in headache-free period of migraine patients and investigate its relation to vascular risk factors. Material and Methods.— Sixty-one patients with episodic migraine headaches and 64 control subjects were enrolled in the study. Demographic data and anthropometric measurements were obtained from all participants; body mass index and fat mass values were calculated. Glucose and lipid parameters were measured by oxidase technique and cholesterol esterase enzymatic assays, and leptin levels were measured by ELISA in serum samples obtained after an overnight fasting. Results.— Leptin levels were found significantly lower in migraineurs than controls (40.1 ± 21.2 ng/mL, 48.5 ± 24.5 ng/mL; P < .05). Although body mass index did not differ between 2 groups, fat mass, and fat percentages were significantly lower in migraine patients (19.4 ± 8.8 kg, 26.0 ± 8.7 kg; P < .001 and 28 ± 9%, 34 ± 5%; P < .001, respectively). Conclusion.— Migraine patients have low leptin levels and fat mass which may be related to the pathogenesis of migraine. The importance and impact of our findings on the prevalence, characteristics, and treatment of migraine needs to be investigated in further detailed studies.

Electric field effect in a GaAs/AlAs spherical quantum dot

Abstract: Using a variational procedure within the effective-mass approximation we calculate the binding and normalized binding energy (NE bF ) of a shallow donor impurity in a GaAs/AlAs spherical quantum dot, under the action of constant uniform electric field applied in the z -direction. A proper choice of the dot radius and electric field can largely change NE bF of a centre shallow impurity in the spherical quantum dot, which may be used to feel the small change in the dot radius.

The impact of Neonatal Resuscitation Program courses on mortality and morbidity of newborn infants with perinatal asphyxia

Abstract: Objective. Neonatal care provided within the first few minutes of life plays a major role in the reduction of neonatal morbidity and mortality. Neonatal Resuscitation Program (NRP) courses had been held since 1996. The aim of this study was to evaluate the impact of the NRP on morbidity and mortality of newborn infants with perinatal asphyxia. Methods. This retrospective study comprised newborn infants who were born in hospitals at Trakya region of Turkey during the last 3 years and were diagnosed as perinatal asphyxia and were referred to our Neonatal Unit. Those patients who were referred before NRP course (pretraining period) were designated as Group 1, those who were referred after the first NRP course (transition period) as Group 2, and those who were referred after the second NRP course (post-training period) as Group 3. Chart review was performed with regard to gestational age, birth weight, Apgar scores, resuscitation type, stage of hypoxic ischemic encephalopathy (HIE), existence of meconium aspiration syndrome (MAS), progress of the disease, duration of hospitalization. Results. The study comprised 66 patients; 35 in Group 1, 18 in Group 2 and 13 in Group 3. The number of cases who had not been resuscitated was 10 in the pretraining period, 3 in the transition period and 1 in the post-training period which decreased significantly. The first minute Apgar scores in three groups were as follows; 2.08 ± 1.2, 2.2 ± 1.1 and 3.7 ± 1.4, and this increase was statistically significant. The fifth minute Apgar scores also increased from 5.43 ± 1.5 in the pretraining period to 6.5 ± 1.9 in the post-training period, but this increase was not statistically significant. The number of patients with Stage 1 and 2 HIE decreased more in Group 3 (n = 11 in Stage 1 HIE, n = 17 in Stage 2 HIE) compared to those in Group 1 (n = 7 in Stage 1 HIE, n = 5 in Stage 2 HIE) but the difference was not statistically significant. The duration of hospitalization decreased in post-training period (15.1 ± 10.3 days in pretraining period, 12.0 ± 8.9 days in transition period, 6.1 ± 1.2 days in post-training period). Conclusions. After NRP courses, the number of patients with perinatal asphyxia and with no resuscitation and also the duration of hospitalization decreased significantly, whereas the first minute Apgar scores increased significantly.

Protective Effects of Vitamin C on Cisplatin-Induced Renal Damage: A Light and Electron Microscopic Study

Abstract: The present study was performed to investigate whether the chronic administration of antioxidant vitamin C provided morphological protection on cisplatin-induced renal damage. Wistar albino male rats were divided into control and two experiment groups, each consisting of six rats. Cisplatin (5 mg/kg/month) was administered intravenously to the second and third group for three months. After the first application of cisplatin, vitamin C (8 mg/kg/day) to the third group was administered intramuscular for 3 months. At the end of the third month, the kidney specimens of the all groups were obtained. All of these kidney specimens were processed for light and electron microscopical examination. In the second group, most of the renal corpuscle lost their normal appearance and size, especially in the corticomedullary region. The most obvious changes were encountered in the proximal tubules. These changes were tubular dilation, thickening of basement membrane, loss of brush border, vacuolization, and swollenness of...

A liquid diffusion model for thin-layer drying of rough rice

Abstract: In this study, the drying behavior of single-layer rough rice with a moisture content of between 22 and 24% on the dry basis was simulated by means of a liquid diffusion model, based on a prolate spheroid geometry. For this purpose, the solution of liquid diffusion equation was fitted to the experimental moisture ratios for drying air temperatures between 40 and 60 °C and velocity 1.5 m s−1. In order to make a comparison, the predictions of liquid diffusion equations for a spherical and finite cylindrical geometry were also fitted to the experimental results. Modeling was performed by selecting the diffusion coefficients in diffusion equations in such a manner as to minimize the sum of the squared differences between the experimental results and the theoretical predictions. It was found that the liquid diffusion model, based on a prolate spheroid geometry, explains single-layer drying behavior of rough rice well. It was also found that the model, based on a prolate spheroid geometry, has better agreement with the experimental results than the other geometries.

Protective effects of Nigella sativa on the neuronal injury in frontal cortex and brain stem after chronic toluene exposure.

Abstract: The goal of this study was designed to evaluate the possible protective effects of Nigella sativa (NS) on the neuronal injury in the frontal cortex and brain stem after chronic toluene exposure in rats. The rats were randomly alotted into one of three experimental groups: A (control), B (toluene treated) and C (toluene treated with NS); each group contain 10 animals. Control group received 1 ml serum physiologic and toluene treatment was performed by inhalation of 3,000 ppm toluene, in a 8 h/day and 6 day/week order for 12 weeks. The rats in NS treated group was given NS (in a dose of 400 mg/kg body weight) once a day orally by using intra gastric intubation for 12 weeks starting just after toluene exposure. Tissue samples were obtained for histopathological investigation. To date, no histopathological changes of neurodegeneration in the frontal cortex and brain stem after chronic toluene exposure in rats by NS treatment have been reported. In this study, chronic toluene exposure caused severe degenerative changes, shrunken cytoplasma, severely dilated cisternae of endoplasmic reticulum, markedly swollen mitochondria with degenerated cristae and nuclear membrane breakdown with chromatin disorganization in neurons of the frontal cortex and brain stem. The nerve cells showing the pathologic changes were almost absent in the NS-treated rats. We conclude that NS therapy causes morphologic improvement on neurodegeneration in frontal cortex and brain stem after chronic toluene exposure in rats. We believe that further preclinical research into the utility of NS may indicate its usefulness as a potential treatment on neurodegeneration after chronic toluene exposure in rats.

Proficiency and knowledge gained and retained by pediatric residents after neonatal resuscitation course.

Abstract: Background: In previous studies the efficacy of the Neonatal Resuscitation Program (NRP) was evaluated, demonstrating good retention of knowledge in the participants. The aim of the present study was to evaluate the knowledge and proficiency that pediatric residents gained and retained following NRP and to determine the necessity and timing of the refresher courses. Methods: The study consisted of 42 pediatric residents who were divided into three groups. Group 1 included pediatric residents who attended the course 1 year previously (n = 18); group 2, 6 months previously (n = 12); and group 3 included those residents who had not attended the NRP previously (n = 12). A written test consisting of 100 questions was applied, and endotracheal intubation skill on a neonatal manikin was evaluated. Results: The percentage of correct answers of participants in groups 1 and 2 decreased similarly during the 6 month and 1 year time period following previous courses. After the new NRP the correct answers increased significantly in groups 1 and 2. The duration of intubation attempt was 17.8 ± 6.0 s in group 1, 17.5 ± 1.5 s in group 2, and 22.3 ± 2.6 s in group 3 before the course and decreased after the course to 10.9 ± 2.0 s in group 1, 10.3 ± 1.5 s in group 2, and 11.7 ± 1.6 s in group 3. The knowledge missing after 6 months and 1 year were similar, while intubation skill decreased after 1 year following the course. Conclusions: Due to worsening of test findings at 6 months after NRP, and deterioration of performance of intubation 1 year after NRP, it is suggested that a refresher course may be required every year.

Effects of shear deformation on vibration of doublewalled carbon nanotubes embedded in an elastic medium

Abstract: In this study, free vibration of simply supported multi-walled carbon nanotubes (CNTs) embedded in an elastic medium was investigated by using the generalized shear deformation-beam theory (GSDBT). The effects of surrounding elastic medium, which is considered as a spring, defined by the Winkler model, and van der Waals forces from adjacent nanotubes are taken into account. Third-order shear deformation (TOSD) theory is used to study free vibration of a multi-walled carbon nanotube embedded in an elastic medium. Unlike Timoshenko beam theory, TOSD theory satisfies zero traction boundary conditions on the upper and lower surface of the structures, so there is no need to use a shear correction factor. Free vibration frequencies and amplitude ratios were obtained for various sides to thickness ratios and elastic medium effects and results are compared with previous studies. The results showed that significant difference exist between TOSD and Euler beam theory. It is also interesting to note that, although frequency parameter is increasing by increasing stiffness of embedded medium, amplitude ratios are insensitive to stiffness of embedded elastic medium.